On my none thumper winter project - GPZ500 - I've put another engine into a rolling chassis I bought off Ebay with a V5C. The engine has come from my other GPZ which is also registered in my name on the V5C. On the DVLA website it states one of the following is needed : a receipt for the replacement engine, written evidence from the manufacturer, an inspection report for insurance purposes, or written confirmation on headed notepaper from a garage if the change took place before you bought the vehicle. I'm inclined to try emailing Kawasaki but am aware manufacturers are generally only interested in selling new models these days. Does anyone have any experience of this please?